Vegetarians who might never have set foot in a fast-food restaurant now drop into Sweden’s Max Burger for its veggie Greenburgare, bean salad and a Lyxshake Jordgubb (strawberry milk shake).

Max Burgers isn’t alone — fast-food chains elsewhere have also started burnishing their green credentials in recent years, with positive sales results. In the U.S., the Mexican-food chain Chipotle — which sources many of its ingredients locally and buys nearly half its beans from organic farms — has tripled its revenues since 2006 to $2 billion and now has more than 1,200 stores. Naked Pizza, which launched in 2009 in New Orleans and serves pies topped with hormone- and antibiotic-free meats, has plans to expand to 500 stores worldwide from its current 24. And in 2010, a vegetarian chain called Otarian launched in New York City and London with menus showing the amount of carbon dioxide emitted while making each food item (1.37 kg for a mushroom-quinoa burger) as well as the amount emitted by the typical fast-food equivalent (2.96 kg for a beef burger). Customers can store up the difference on a “Carbon Karma” card and redeem it for a free menu item of their choice.